In noise-mitigating headset designs, passive noise control approaches have shown substantial broadband reductions of high frequency noise using well-sealed ear defenders lined with sound absorbing material such as high-density foam. The materials of the headphones themselves also block out some sound waves, especially those at higher frequencies. The sound absorbing material makes them heavier than normal headphones. The tradeoff of all that extra weight is a reduction in noise of about 15 to 20 decibels (dB). In some cases, people working in a noisy environment all day do not wear ear defenders as often times they can be uncomfortable to wear for long periods of time and the headsets tend to limit speech intelligibility.